Geoscience Reference
In-Depth Information
much red-blooded damage you could do with one little squeeze of a trigger. The grizzly was the worst.
When it came into camp, it made an angry beeline for the helicopter. It had probably been buzzed by
some idiot joy-riders and was out for revenge. That was hardly the bear's fault, but the helicopter was
too precious to risk. As Paul loaded the rifle, he felt sick. Afterwards the same helicopter slung the
grizzly's body back out into the bush.
Paul knew that he couldn't afford to let the flies or bears get to him psychologically, so he never
did. Gradually he got used to them both. After a few weeks of building up tolerance, he found that
new fly bites didn't swell so much. And if you could ever see beyond the buzzing, whirring, whining
clouds that enveloped you, the landscape was vast, empty and gorgeous. There were no trees to block
the skyline, just mile upon mile of rounded rocks and the boggy Arctic vegetation known as muskeg.
Air and light both had a clarity that Paul had never experienced before. During the fleeting summer
months of his field season, when the outer vestiges of winter melted briefly, there were ponds and
pools and lakes of water everywhere. The ground squelched underfoot. The only sound came from
the nesting birds, loudly defending their soggy territories and raising their young. Even they quietened
down at night, although the midnight sun still shone then. All day long the sun was low on the horizon,
and at midnight it reached its lowest point. Then the sunlight slanted most steeply of all, and the shad-
ows were dramatic and long.
The short summer and continuous daylight put everything into overdrive. Eggs hatched into
fledglings and then grew into birds that were ready to leave their nests in a matter of weeks. Flowers
appeared in the scrapings of soil between rocks and among the spongy mosses and lichens of the mus-
keg and then vanished again almost immediately. Summer after summer Paul returned to the Arctic,
now a fully-fledged geologist for the Survey. He strode out his rock contacts, mapped his terrains,
noted down the rock types and their structures. He worked sixteen to eighteen hours a day. There was
no sign that any other human had ever set foot there. Paul felt that he was master of the landscape.
The rocks he was working on were among the oldest in the world. They came from a catch-all time
that geologists call the Precambrian, because it led up to the Cambrian period—which heralded one of
the most significant changes in the history of the Earth. Naming time slices by what comes afterwards
is a peculiar geological habit. More peculiar than ever in this case, because the Precambrian is much
more than just a slice of time. The Precambrian lasted 4 billion years, covering nearly 90 per cent of
Earth's entire history.
And yet, to geologists, this has long been considered the Earth's Dark Age. Plenty may have been
happening, but nothing was recorded for posterity. The rocks of the Precambrian are like the history
topics of Europe's medieval Dark Ages—a blank. What was missing? Fossils. Geologists rely heavily
on fossils. One rock can look much like another, and to find out when exactly it was formed you need
to look at the creatures that are locked inside. The Cambrian, roughly 550 million years ago, is the
time when serious fossils first appear in the rocks. If you look at a section of rock from the beginnings
of the Cambrian, you start to see real creatures with legs and teeth and armour plating, and you see
changes in the fossils over time. In more recent rocks, dinosaurs appear and then vanish, making way
for the fossils of mammals, fish and birds. Each has its own season and time, and each dates the rock
that houses it. Fossils provide a ready-made timescale. They are like clocks left frozen in the rock.
Every slice of geological time that comes after the Cambrian can be divided into periods and eons,
according to the creatures that lived then.
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But before the Cambrian there were no fossils to speak of. And the few algae and the simple,
single-celled creatures of Slime-world that did bequeath their forms to the rocks stayed more or less
the same for billions of years. Because of this, the rocks of the Precambrian just merge together into
